Amidocarbonylation is, for the purposes of the present invention, the carbonylation of carboxamides in the presence of aldehydes and carbon monoxide or synthesis gas to give N-acyl-alpha-amino acid derivatives. This reaction is carried out in the presence of cobalt carbonyl compounds as homogeneous catalysts. The use of fatty acid amides as amide components and formaldehyde as aldehyde components makes it possible to employ this process to access the class of N-acylsarcosines which are used industrially as surfactants, soaps and emulsifiers.